POLVETIIYLEXE CABLE 8IIEATI1 THICKNESS 



561 



Pig. 2 — Typical core tulie and die. 



they are onl}- short pieces to represent cables up to a few thousands of 

 feet in length. 



Sheath eccentricity is expressed as a percentage and is the difference 

 between the thicknesses, of the thickest and the thinnest sides of a cross 

 section, in relation to the specified Avail thickness expressed in mils. 

 Control from end sampling resulted in most cables ha\'ing eccentricities 

 of 30 per cent to 60 per cent. Also, it was difficult to keep the average 

 thickness to within ±0.010 inch of the specified average thickness. 



The need for a better gaging method than end sampling, led to an 

 investigation of detennining the wall thickness in terms of the capaci- 

 tance that would be fomiod l)}^ the metal luidersheath and a probe sliding 

 on the sheath svu-face. 



A test set as shoA\Ti in Fig. 5 was developed which I'osponds to changes 



